1. Field of the Invention
The present invention relates to a support for a lithographic printing plate and a presensitized plate, more particularly to a presensitized plate with a high strength where a fatigue fracture does not easily occur, even when the plate is mounted on a plate cylinder of a printing machine with a high tensile force, an anodized layer may not be easily cracked and having an excellent resistance to aggressive ink staining, and a support for a lithographic printing plate used therefor.
In addition, the present invention more particularly relates to a support for a lithographic printing plate where a material cost can be largely reduced, with a very fine crystal grain, excellent surface quality (appearance) and the excellent press life and relates to a presensitized plate using the support.
2. Description of the Related Art
A photosensitive presensitized plate having an aluminum plate as a support is widely used for an offset printing. A presensitized plate is typically manufactured by performing a graining treatment on a surface of an aluminum plate, performing an anodizing treatment, thereafter applying a photosensitive solution and drying the plate so as to form a photosensitive layer (an image recording layer). After the presensitized plate is exposed to an image, it is developed by a plate developer, an exposed portion in case of a positive presensitized plate or a non-exposed portion in case of a negative presensitized plate is removed and plate making is performed, thus a lithographic printing plate is manufactured. In addition, in recent years, a manufacturing method of a presensitized plate using a laser attracts attention and various methods are studied. For example, there is known a photon-system laser lithographic plate using a photopolymerizable composition which is hardened by a visible light laser and a heat mode-system laser lithographic plate using heat or the like generated by a laser light irradiation to record. These systems are very useful since plate making can be performed directly from a digital data in a computer or the like to manufacture a lithographic printing plate.
The lithographic printing plate thus manufactured is then mounted on the plate cylinder of a printing machine, an ink and a fountain solution are supplied to a surface thereof. As they are used for printing, the remaining portion of a photosensitive layer becomes an image area showing an ink affinity, a portion in which a photosensitive layer is removed becomes a non-image area showing a water wettability, thus, it is transcripted on a blanket cylinder and is printed on paper.
As is seen from the foregoing, in a presensitized plate, the physical properties of a photosensitive layer are changed by exposure, and plate making is performed utilizing the changes in the physical properties.
As mentioned above, when a developing processing is performed on a presensitized plate after an image is exposed, there is a case where a surface of a non-image area may be partially eroded by a plate developer, thereby resulting in the deterioration of resistance to aggressive ink staining depending on the conditions of the plate developer. In addition, there is a defect where the level of resistance to aggressive ink staining largely changes depending on whether or not alkali metal silicate is contained in a plate developer. Here xe2x80x9caggressive ink stainingxe2x80x9d is defined as a defect that inks are attached to a non-image area of a lithographic printing plate in a dotted state or a circular state, thereby resulting in a dotted or a circular scum on paper if printing is intermittently performed many times.
To improve resistance to aggressive ink staining, a number of proposals are presented. Concretely, there are many proposals to specify alloy components contained in an aluminum plate used for a support for a lithographic printing plate. For example, a method by specifying alloy components such as Mg, Mn, Si, Ga, Ti, Cu (JP 5-309964 A, JP 3-177528 A or the like), a method by specifying a ratio of Fe to Si (JP 4-254545 A, JP 7-197162 A or the like), a method by specifying the content of a solid solution of Fe (JP 4-165041 A or the like), a method by specifying a simple Si content (JP 2544215 B, JP 2031725 B or the like), a method by specifying a content, size, distribution or the like of intermetallic compounds (JP 4-165041 A, JP 3-234594 A, JP 2544215 B, JP 4-254545 A or the like) and a method by specifying the characteristics of an anodized layer in combination with specifying alloy components (JP 7-197393 A, JP 7-26393 A or the like) are described.
Since there has been increasing variety of presensitized plates such as a laser direct recording-type presensitized plate and a conventional analog-type presensitized plate, and the exposure and development have been processed in combination with various plate developers corresponding to image recording layers and the features in their applications, it has been a large problem to control a printing performance which may vary with a plate developer.
In the meantime, efforts to improve various performances of the presensitized plate have been conducted by controlling trace components of aluminum alloys. Since this method is to add only a trace of a certain component to an aluminum alloy, it is advantageous in a point that this addition does not affect the physical properties of a presensitized plate at all.
For example, the inventors of the this application have proposed that the efficiency of electrochemical graining treatment (electrolytic graining treatment) on an aluminum plate may be improved by having the aluminum plate contain, in addition to Fe: 0.05 to 0.5 wt %, Si: 0.03 to 0.15 wt %, Cu: 0.006 to 0.03 wt % and Ti: 0.010 to 0.040 wt %, 1 to 100 ppm of at least one kind element selected from a group consisting of Li, Na, K, Rb, Cs, Ca, Sr, Ba, Sc, Y, Nb, Ta, Mo, W, Tc, Re, Ru, Os, Co, Rh, Ir, Pd, Pt, Ag, Au, C, Ge, P, As, S, Se, Te and Po. (JP 2000-37965 A).
The assignee of this application has proposed that the electrochemical graining characteristic may be further improved by having the aluminum plate contain, in addition to the elements mentioned above, 10 to 200 ppm of Mg, resulting in the improved contact characteristics between the image recording layer and the support in a laser direct-recording type presensitized plate, and in the improved press life of the lithographic printing plate (JP 2001-162958 A).
Moreover, the assignee of this application has proposed to improve the efficiency of electrolytic graining and press life by specifying the concentration of Cu in a depth direction in the vicinity of the surface of an aluminum plate and the relationships between Cu, Si and Ti as well as by adding the foregoing elements (Japanese Patent Application No. 2001-25370).
Since the proposals on the addition of these trace components are, however, not intended to improve resistance to aggressive ink staining, the resistance to aggressive ink staining is not necessarily adequate.
In the meantime, a lithographic printing plate is bent at both ends when it is mounted on a printing machine plate cylinder. Each of the bent portions is fixed in two clamps called gripper portion and gripper edge of printing machine plate cylinder section, after applying tensile force so as to have a lithographic printing plate closely contact with the blanket cylinder, and then the lithographic printing plate is used for printing. Here is a defect that the two bent portions at both ends of the lithographic printing plate are likely to rise out of the plate cylinder due to a reaction force against the bending, therefor, if the plate cylinder is repeatedly pressed to the blanket cylinder under this condition, fatigue fracture is likely to take place since the risen portion is repeatedly bent.
Although this rise may be suppressed by increasing a tensile force applied to the plate when the plate is mounted on the plate cylinder, the lithographic printing plate itself needs a high tensile strength for this purpose. In addition, the inventors of the present invention, on close research and study, have found that if a high tensile force is applied to the lithographic printing plate, an anodized layer existent on its surface is damaged such as being cracked, thereby causing stain during printing.
On a lithographic printing plate, a heating processing called burning-in processing (post-baking processing) is also generally conducted after performing exposure and development. Burning-in processing is normally conducted at a temperature of 200xc2x0 C. or higher, particularly it is mostly conducted at approx. 240 to 270xc2x0 C. although it depends on purposes. Press life is improved by further hardening the photosensitive layer of an image area, thereby enabling a larger number of printings. This is because an abrasion during printing is suppressed by hardening the photosensitive layer of an image area.
However, if this burning-in processing is conducted, a problem may arise that a recrystallization or recovery in an aluminum plate takes place, thereby deteriorating the strength of the plate.
Many proposals have been presented in regard to the deterioration of the strength after the burning-in processing is performed. For example, JP 4-73394 B and JP 7-126820 A propose that 0.2% strength after heating or the like should be specified. JP 7-39906 A proposes that a diameter of a crystal grain equivalent to that of a circle in the cross section of a plate should be defined. JP 7-305133 A proposes that a solid solution amount of Fe should be specified.
A number of measures by specifying alloy components are proposed. For example, JP 5-501585 A, U.S. Pat. No. 5,009,722, JP 4-19290 B and U.S. Pat. No. 5,114,825 propose a method by adding Mn. JP 5-462 B, JP 6-37116 B, JP 4-73392 B, JP 3-68939 B and JP 3-11635 B propose a method by adding Mg. JP 5-76530 B and JP 5-28197 B propose a method by adding both Mn and Mg. Moreover, JP 4-72720 or the like proposes a method by adding Zr independently or in combined with Mn or Mg mentioned above.
In the method by defining 0.2% strength or the like after heating, described in JP 4-73394 B, JP 7-126820 A or the like, in the method by defining a diameter of crystal grain equivalent to that of a circle in the cross section of a plate described in JP 7-39906 A, and in the method by specifying a solid solution amount of Fe described in JP 7-305133 A, the drop rate of the tensile strength after burning-in processing is performed becomes smaller, demonstrating an effect to some extent. However, there is a defect that the fatigue fracture of a lithographic printing plate may take place while a large number of printings are repeated.
In addition, although the method by adding Mn or Mg has an effect to prevent the fracture of a plate during printing, the resistance to aggressive ink staining is not always adequate since the method is not intended to improve the resistance to aggressive ink staining.
Therefore, it is the first object of the present invention to provide a support for a lithographic printing plate such that (1) a plate has an excellent resistance to aggressive ink staining against a wider range of image recording layers and plate developers corresponding thereto, (2) a fatigue fracture does not easily take place in a plate since the plate has a high strength, and the adequate strength of a plate is still maintained even after burning-in processing is performed and (3) even when a plate is mounted on a printing machine plate cylinder with a high tensile force, an anodized layer is not easily cracked, when the presensitized plate is prepared, by adding a trace of specified components to an aluminum plate used, and a lithographic printing plate using the support for a lithographic printing plate.
In addition, a support for a lithographic printing plate is conventionally manufactured by performing graining treatment on one side or both sides of an aluminum alloy plate and anodizing treatment for improving abrasion resistance. A presensitized plate is manufactured by providing a photosensitive layer on the support for a lithographic printing plate. In addition, a fine profile irregularities called a mat layer may be provided on the surface of the photosensitive layer in order to shorten a vacuum contact time at the time of plate making.
A lithographic printing plate is prepared by various types of plate making processings such as image exposure, development, water washing or the like on a presensitized plate thus manufactured. The following methods for image exposure are used; a method by differentiating an image area from a non-image area by contacting a lith film to which the image is printed and irradiating, a method by differentiating an image area from a non-image area with a method by directly recording the image area or the non-image area by using a laser or projecting an image.
When a development processing is performed after image exposure, an undissolved photosensitive layer forms an image area as an ink receptor, and in an area from which a photosensitive layer is removed by being dissolved, an aluminum alloy or an anodized layer beneath the area is exposed, which forms a non-image area as a water receptor. If required, treatment for water wettability, gumming, burning-in processing or the like may be performed after development.
This lithographic printing plate is mounted on a cylinder-shaped printing machine plate cylinder, to which an ink and a fountain solution are supplied, thereby enabling the ink to be attached to an image area having ink receptivity and the water to be attached to a non-image area having water wettability. After the ink of the image area is transferred to a blanket cylinder, an image is printed on paper from the blanket cylinder. If a contact between the photosensitive layer of the image area and the support is inadequate, a problem that printing terminates with a small number of sheets of papers may take place. As a method of improving a contact between the photosensitive layer of the image area and the support, the following methods are known; i.e., a method by providing an intermediate layer between an aluminum alloy plate and the photosensitive layer, and a method by evenly performing a graining treatment on an aluminum alloy plate or the like are known.
The following can be used as an intermediate layer for undercoating; i.e., amino acids and their salts (alkali metallic salts such as Na salt, K salt or the like; ammonium salt; hydrochloride; oxalate; acetate: phosphate or the like) as described in JP 60-149491 A, amines having hydroxy group and their salts (hydrochloride, oxalate, phosphate or the like) as described in JP 60-232998 A, compounds having amino group and phosphonic group and their salts as described in JP 63-165183 A. In addition, compounds having phosphor group as described in JP 4-282637 A can be used as an intermediate layer. Moreover, it is known that high molecular compounds containing acid group and onium group as described in JP 11-109637 A are used as an intermediate layer after alkali metallic silicate processing is performed. However, in a method by providing an intermediate layer for contact between a grained surface and a photosensitive layer, there is of course a problem that a manufacturing cost for providing an intermediate layer becomes higher.
In the meantime, there is known a method by specifying alloy components which are contained in aluminum alloy and largely affect graining treatment.
Many proposals are described as a method by specifying alloy components. For example, concerning JIS 1050 materials, the inventors of the present invention have described the related arts in JP 59-153861 A, JP 61-51395 A, JP 62-146694 A, JP 60-215725 A, JP 60-215726 A, JP 60-215727 A, JP 60-215728 A, JP 61-272357 A, JP 58-11759 A, JP 58-42493 A, JP 58-221254 A, JP 62-148295 A, JP 4-254545 A, JP 4-165041 A, JP 3-68939 B, JP 3-234594 A, JP 1-47545 B and JP 62-140894 A. In addition, JP 1-35910 B, JP 55-28874 B and the like are also known as the related ones. Regarding JIS 1070 materials, the inventors of the present invention have described the related arts in JP 7-81264 A, JP 7-305133 A, JP 8-49034 A, JP 8-73974 A, JP 8-108659 A and JP 8-92679 A.
Regarding Alxe2x80x94Mg system alloys; the inventors of the present invention have described the related arts in JP 62-5080 B, JP 63-60823 B, JP 3-61753 B, JP 60-203496 A, JP 60-203497 A, JP 3-11635 B, JP 61-274993 A, JP 62-23794 A, JP 63-47347 A, JP 63-47348 A, JP 63-47349 A, JP 64-61293 A, JP 63-135294 A, JP 63-87288 A, JP 4-73392 B, JP 7-100844 B, JP 62-149856 A, JP 4-73394 B, JP 62-181191 A, JP 5-76530 B, JP 63-30294 A and JP 6-37116 B. JP 2-215599 A and JP 61-201747 A are also known.
Regarding Alxe2x80x94Mn system alloys, the inventors of the present invention have described the related arts in JP 60-230951 A, JP 1-306288 A and JP 2-293189 A. JP 54-42284 B, JP 4-19290 B, JP 4-19291 B, JP 4-19292 B, JP 61-35995 A, JP 64-51992 A, U.S. Pat. No. 5,009,722, U.S. Pat. No. 5,028,276, JP 4-226394 A and the like are also known.
Regarding Alxe2x80x94Mnxe2x80x94Mg system alloys, the inventors of the present invention have described the related arts in JP 62-86143 A and JP 3-222796 A. JP 63-60824 B, JP 60-63346 A, JP 60-63347 A, EP 223737 A, JP 1-283350 A, U.S. Pat. No. 4,818,300, GB 1222777 and the like are also known.
Regarding Alxe2x80x94Zr system alloys, the inventors of the present invention have described the related arts in JP 63-15978 B and JP 61-51395 A. JP 63-143234 A, JP 63-143235 A and the like are also known. Regarding Alxe2x80x94Mgxe2x80x94Si system alloys, GB 1421710 and the like are also known. All of them, however, are intended to limit aluminum materials and have demerits that lower freedom of selection of materials and require high-priced new metals and predetermined elements to be added for alloy.
These alloys are manufactured in the following processings; i.e., normally raw material chiefly composed of aluminum is dissolved, to which predetermined metals are added to prepare an aluminum alloy molten metal of a predetermined alloy component, a purifying processing is then performed on the aluminum alloy molten metal and casting is finally performed. In the purifying processing, the following steps are taken to remove unnecessary gas such as hydrogen in the molten metal; i.e., flux processing; degassing processing using Ar gas, Cl gas or the like; filtering using so-called rigid media filters such as ceramic tube filter, ceramic form filter, filters with filtering materials of alumina flake, alumina ball or the like, and glass cloth filters or the like; processing combining degassing processing with filtering, or the like. It is preferable that these purifying processings shall be performed to prevent a non-metallic inclusion in the molten metal, a defect caused by foreign matters such as oxides and a defect caused by gases dissolved in the molten metal.
As is seen from the foregoing, casting is conducted by using a molten metal on which each purifying processing has been performed. As for casting methods, there are one method using a fixed mold which is represented by DC casting method and another using a driven mold which is represented by continuous casting method.
With DC casting method, a cooling speed is set at a range of 1 to 300xc2x0 C./sec. Although in this processing the aforementioned alloy component elements are partially dissolved in aluminum, the components which can not be dissolved in the aluminum form various intermetallic compounds, which remain in an ingot. DC casting method can manufacture an ingot of 300 to 800 mm in thickness and on which facing is performed in accordance with the normal method, the ingot is cut by 1 to 30 mm in depth from a surface layer, preferably 1 to 10 mm deep. Thereafter, soaking processing is performed as required. Unstable intermetallic compounds are converted into stable ones and a part of them are dissolved in aluminum by performing soaking processing. After the soaking processing, although remaining intermetallic compounds become smaller in diameter or are dispersed during hot rolling and cold rolling, the kinds thereof remain almost intact. Namely, they finally remain on an aluminum alloy plate, that is, a support for a lithographic printing plate.
Also, a thermal processing called annealing may be performed before and after or during cold rolling. In this case, a part of elements dissolved in aluminum may deposit as deposit of intermetallic compounds or a simple element depending on the temperature of a thermal processing of annealing. Also in this case, the deposit remains in an aluminum alloy plate.
The aluminum alloy plate finished to a predetermined thickness (0.1 to 0.5 mm) by cold rolling may be subjected to flatness improvement processing of by a correcting equipment such as a roller leveler or tension leveler.
As a casting method, a continuous casting method may be used. The following methods can be used; i.e., two-rolling continuous casting method represented by Hunter method or 3C method, two-belt continuous casting method represented by belt caster of Husrey method and block caster of Alusuisse method or the like. For example, if a two-rolling method used, a cooling speed is set at a range of 100 to 1,000xc2x0 C./sec. In the meantime, if a two-belt method is used, a cooling speed is set at a range of 10 to 500xc2x0 C./sec. In any method, a plate with a determined thickness (0.1 to 0.5 mm) is prepared by cold rolling or rolling processing combining hot rolling with cold rolling, after casting is performed. Also, a thermal processing may be performed if necessary during these processings. An aluminum alloy plate finished with a predetermined thickness by cold rolling may be subjected to flatness improvement processing by correcting equipment such as roller leveler and tension leveler. Since these continuous casting methods are characterized by being capable of dispensing with facing process which is required by DC casting method, it has a merit that the running cost is smaller than that of DC casting method.
Since aluminum as a raw material is prepared to be a predetermined alloy component, an aluminum ingot of a purity 99.7% or higher called a new metal is used or aluminum rubbish generated from manufacturing processes in an aluminum plant, of which an alloy component is known is used. An aluminum alloy called a master alloy containing predetermined elements is added or a metal ingot composed of predetermined elements is added as required, thus an aluminum alloy material having a predetermined alloy component is manufactured.
However, an aluminum alloy material containing new metal or predetermined element components being added has a demerit that it is high-priced. If aluminum rubbish generated from manufacturing processes in an aluminum plant with a known alloy components is used, there is a merit that the recovery rate of raw material is improved. However, the cost is not very low.
In an effort to overcome the problem that a raw material is high-priced, the inventors of the present invention have proposed a method that an aluminum ingot of purity 99.7% or higher only is used to dispense with a master alloy or a metal ingot containing predetermined elements in JP 7-81260 A. The inventors of the present invention have also proposed a method of recycling an end-of-life lithographic printing plate or a lithographic printing plate which becomes defective under a manufacturing process as an aluminum raw material in JP 7-205534 A.
Even though these methods are used, the cost of an aluminum ingot of purity 99.7% or higher can not be largely reduced, and a large practical effect can not be obtained since it is rather difficult to secure an end-of-life lithographic printing plate as a stable raw material.
In order to solve the aforementioned problems, use of a material of which an alloy component is not controlled, that is, scrap that contains various impurities, or secondary metal or metal called regenerated metal containing many impure elements which are rather lower market-priced than that of new metal as raw materials may be considered. However, since almost no control is made on alloy components in these materials, they could never be used for the raw material which requires a high-quality appearance after surface treatment and printing performance as in a lithographic printing plate. Particularly, there is a problem that the press life is inferior since even graining can not be obtained, and thus a contact with a photosensitive layer is inadequate.
In the meantime, the inventors of this application have already proposed in Japanese Patent Application No. 2001-90960 the following support for a lithographic printing plate based on an aluminum alloy plate that an aluminum content is 94 to 99.4 wt %: a support for a lithographic printing plate where at least graining treatment and anodizing treatment are performed on the aluminum alloy plate; moreover, a support for a lithographic printing plate containing an aggregate content of Si and Mn, 0.5 wt % or higher; a support for a lithographic printing plate, on a grained surface of which intermetallic compounds with a diameter of 0.1 xcexcm or larger, partially exist by 5,000 to 35,000 pcs/mm2; a support for a lithographic printing plate containing Cu by 0.05 wt % or more; a support for a lithographic printing plate where the raw material of these aluminum alloy plates contain at least one kind of an aluminum regenerated metal and aluminum scrap or the like by 1 wt %.
The inventors of this application have filed the application since it has been found that this method can reduce the cost of Al raw material and a contact between a photosensitive layer and a support can be improved by increasing the density of intermetallic compounds with a diameter of 0.1 xcexcm or larger existing on the surface more than that of conventional materials.
The inventors of the present invention, however, have found that on further close examination, an optimum kind of intermetallic compound and a range of density are necessary considering a recent wide variety of image recording layers and the characteristics of the image recording layer and the stability of development processing.
Consequently, it is the second object of the present invention to provide a support for a lithographic printing plate, which has no need to have a high-priced intermediate layer, no need to perform a graining treatment under a special condition, uses an extremely lower-priced material and has excellent appearance of the surface of the support, and where a contact between a photosensitive layer and the support and thus press life are also excellent, and to provide a presensitized plate using the support for a lithographic printing plate.
The inventors of the present invention, on close examination, have found that resistance to aggressive ink staining of a lithographic printing plate can be improved by having the plate contain a specified content of Mn and/or Mg in an aluminum plate and adding a trace of a specified alloy component thereto, not depending on the conditions of an image recording layer and plate developers, that a content in an aluminum plate is different by element in order to obtain such effect, moreover, that the plate gains such a high strength that fatigue fracture does not easily take place, thus the plate can have a sufficient strength even if burning-in processing is performed, and that even though a plate is mounted on a printing machine plate cylinder with a high tensile force, an anodized layer is not easily cracked, and the inventors have completed the first aspect of the present invention.
That is, the first aspect of the present invention is that a support for a lithographic printing plate obtained by subjecting an aluminum plate to a graining treatment and an anodizing treatment, the support comprising:
at least any one of Mn in a range from 0.1 to 1.5 wt % and Mg in a range from 0.1 to 1.5 wt %;
Fe of 0 to 1 wt %;
Si of 0 to 0.5 wt %;
Cu of 0 to 0.2 wt %;
at least one kind of element out of the elements listed in items (a) to (d) below in a range of content affixed thereto,
(a) 1 to 100 ppm each of one or more kinds of elements selected from a group consisting of Li, Be, Sc, Mo, Ag, Ge, Ce, Nd, Dy and Au,
(b) 0.1 to 10 ppm each of one or more kinds of elements selected from a group consisting of K, Rb, Cs, Sr, Y, Hf, W, Nb, Ta, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, In, Ti, As, Se, Te, Po, Pr, Sm and Tb,
(c) 10 to 500 ppm each of one or more kinds of elements selected from a group consisting of Ba, Co, Cd, Bi and La, and
(d) 50 to 1000 ppm each of one or more kinds of elements selected from a group consisting of Na, Ca, Zr, Cr, V, P and S; and
Al and incidental impurities as a remaining portion.
Therefore, the support for a lithographic printing plate according to the first aspect according to the present invention is very useful, since it shows excellence in resistance to aggressive ink staining against various image recording layers and plate developers corresponding thereto, a high strength and an excellence in resistance to plate fracture, and no dirt resulting from cracking of an anodized layer.
The inventors of the present invention have also found that in order to achieve the second objective of the present invention, a kind of intermetallic compound of an aluminum plate after graining treatment is performed, preferably after anodizing treatment is performed and the density of intermetallic compounds existing on the surface of the plate should be set in specified ranges and have completed the second aspect of the present invention.
That is, the second aspect of the present invention is to provide a support for a lithographic printing plate obtained by subjecting an aluminum plate with an aluminum content 95 to 99.4 wt % to a graining treatment, the support comprises three kinds of intermetallic compounds or more, wherein one kind or more of intermetallic compounds consist of two kinds of elements, and one or more kinds of intermetallic compounds other than these intermetallic compounds consist of four kinds of elements, and a density of intermetallic compounds existing on the surface of the support among these compounds ranges 3,000 to 35,000 pcs/mm2. One of the preferred aspects is that the aluminum plate contains 1 wt % or more of at least one kind out of an aluminum regenerated metal and aluminum scrap.
The present invention also provides a presensitized plate having an image recording layer on the support for the lithographic printing plate mentioned above.
One of the preferred aspects is that the image recording layer is of a laser direct recording type thermal sensitive material.
One of the preferred aspects is that the image recording layer is of a laser direct recording type photopolymer sensitive material.
One of the preferred aspects is that the image recording layer is of an analog type thermal sensitive material.
Therefore, according to the second aspect of the present invention, there can be provided with a support for a lithographic printing plate excellent in a contact with a photosensitive layer and press life despite of raw materials containing an extremely cheap materials or regardless of the type of graining treatment, having the kinds of intermetallic compound, and the density of intermetallic compounds existing on the surface of an aluminum plate after graining treatment is performed as indexical properties, and a presensitized plate using the support.
When a lithographic printing plate is prepared from a presensitized plate according to the present invention which uses a support for a lithographic printing plate of the first aspect according to the present invention, a mechanism that resistance to aggressive ink staining becomes excellent and a mechanism that an anodized layer is not easily cracked even if a high tensile force is applied are not clear at present. However, it is considered that the soundness of an anodized layer, chemical resistance and cracking resistance are improved and resistance to aggressive ink staining is thus improved. Concretely, it is considered that intermetallic compounds that are likely to be the trigger of a defect in an anodized layer is converted into a harmless substance and the density of an anodized layer itself is increased by adding a trace of the aforementioned elements.